Packaging method for pressurized dispensers



Sept. 17, 1963 R. w. BATEY PACKAGING METHOD FOR PRESSURIZED DISPENSERS Filed Feb. 16, 1962 INVENTOR. ROBERT W 5 4 TE) ATTORNEYS United states Patent Filed Feb. 16, 1962, Ser. No. 173,710 2 Claims. (Cl. 141-12 This invention relates generally to the packaging art, and more specifically to a new and useful method for packaging and sealing viscous materials in pressurized dispensers.

The aerosol packaging of products to be dispensed offers many advantages, from the viewpoint of convenience to the consumer, and has become extremely popular. A large number of products now are packaged in aerosol dispensers, with the product being mixed with the propellant gas and dispensed through a suitable nozzle. However, this method of packaging is not suitable for products of marked viscosity, because the propellant tends to channel through the product, and the product tends to cling to the container side wall, both resulting in an unacceptably high retention of the product in the container when the propellant is exhausted.

Attempts have been made to package viscous products in pressurized containers wherein the pressure propellant is separated from the product, by either a bag or a tightfitting piston dividing the container into a product section and a propellant section. However, neither of these approaches has achieved any substantial measure of commercial utilization.

'More recently, a free-piston container has been proposed, in which the piston is not tight-fitting in the container, but freely movable therealong, and reliance is placed upon the viscous product to act as a sealant between the piston and the container wall. The existence of an effective seal is mandatory, to prevent the escape of propellant around the piston and into the product. The escaping propellant will channel through the product, taking the path of least resistance, .and thereby blow-by a substantial portion of the product. This not only results in an undesirable degree of product retention, but also disrupts the product flow from the dispenser.

'While a viscous product can by its nature form an effective seal, it cannot be depended upon to do so using standard filling techniques. Normal filling operations, through the reduced diameter opening usually provided at the end of the container, produce voids and air pockets throughout the product and along the container wall. The presence of such voids at the container wall permits the escape of propellant around the piston, and the voids in the product facilitate the undesired channeling action. In addition, the voids or air pockets in the product cause the intermittent escape of air and resultant disruption of the product How from the dispenser.

Accordingly, the primary object of this invention is to provide a method for packaging viscous products in such free-piston containers which will effectively seal the piston, thereby precluding blow-by.

Another object of this invention is to accomplish the foregoing in a manner which does not require highly skilled personnel or extensive equipment, and thereby is economically feasible.

In one aspect thereof, the method of packaging a viscous product in a pressurized dispensing container of the piston type, in accordance with this invention, is characterized by the step of so rotating the container as to produce centrifugal force sufiicient to compact the product against the container wall, thereby sealing the piston.

The foregoing and other objects, advantages and char- Patented Sept. 17, 1963 acterizing features of the packaging method of this invention will become clearly apparent from the ensuing detailed description thereof, taken in conjunction with the accompanying drawing wherein like reference numerals denote like parts throughout the various views and wherein:

FIG. 1 is a longitudinal sectional view, partly in elevation for convenience in illustration, of a free-piston container, showing the condition of the packaged product after conventional filling techniques only have been applied;

FIG. 2 is a similar view, but showing the condition of the packaged product after the method of this invention has been applied;

FIG. 3 is a similar view, showing the condition of the product after the method of this invention has been applied in a slightly different manner; and

FIG. 4 is a schematic representation of one form of apparatus for carrying out the' method of this invention.

Referring now in detail to the accompanying drawing, there is shown in each of the figures a free-piston container of the type which comprises a shell 1, of generally cylindrical wall form, and a bottom end wall 2. At its upper end, the container wall blends into a shoulder 3 providing a neck opening 4 through which the container is filled and which is adapted to receive a cup 5 (FIG. 4) mounting a dispensing nozzle having a rubber connection 7 to cup 5. A suitable dispensing nozzle 6 contains a valve (not illustrated) which is opened by canting nozzle 6 relative to container 1. A gassing opening through bottom end wall 2 is normally closed by a the packaging of a viscous product in such a container,

so as to avoid blow-by. The method of this invention is perhaps best explained by first referring to FIG. 1 illustrating the internal appearance of the container after filling in the usual manner. A viscous material 13, such as a butter-cream icing for decorating cakes and the like, has been introduced into chamber 11 through filling opening 4. This might be done, for example, using a commercially available filler of a type equipped with a nozzle that can enter chamber 11 and fill it from the bottom as the nozzle is withdrawn. When this is done, it will be found that the product usually is deposited in the chamber in folds, or layers, as indicated at 14, which leaves voids 15 along the container wail. Also, entrapped air pockets 16 are dispersed throughout the product itself.

Piston 9 is free-floating and does not itself provide a seal with the container wall. Consequently, the propellant gas in chamber 12 will escape between the piston skirt 10 and the container wall into the product chamber 11. The gas permeates the external voids 15, and comes to a state of equilibrium on opposite sides of piston 9. When dispensing nozzle 6 is actuated to open its internal valve, a pressure differential exists, not at piston 9 as intended, but either at the nozzle or at some intermediate point in the product chamber 11. If it exists at the nozzle, the propellant gas simply escapes at once through the nozzle, and little or no product is dispensed. If the pressure differential exists at an intermediate point in chamber 11, the product will be dispensed only until the point of pressure difierential reaches the nozzle valve, whereupon the pro- 3 pellant gas will escape and the rest of the retained in the container.

Obviously, such escape of propellant and consequent loss of the product retained in the can cannot be tolerated. Containers of this type can be designed to dispense as high as 97% of the fill weight of the product, under proper operating conditions. However, because of the abovenoted problem of blow-by, such containers heretofore have only been practical for use with products of low enough viscosity to be self-conforming to the container configuration.

Also, when air pockets 16 are present in the product 13, even if piston 9 does function the dispensed product will be interrupted with periodic bursts-of escaping air. Instead of a continuous, smooth stream of product from nozzle 6, there will be a periodic escape of air which disrupts the product flow. This makes the product unsuitable where it is desired to have a continuous and unbroken product stream, as in cake decoration, for example.

Therefore, normal filling procedures tend to unevenly distribute the product in the chamber, leaving voids along the container wall whereby the product does not effectively seal the piston, as intended, and leaving air pockets in the product. These undesirable results are avoided with the packaging method of this invention, wherein the container is rotated in a manner generating centrifugal force sutficient to compact the product against the container wall. By way of example, in carrying out the method of this invention the container can be rotated at high speed about its longitudinal axis. As this is done, the product in chamber 11 will move radially outwardly against the container wall and will be compacted against the container wall. This is illustrated in FIG. 2, showing the result obtained when the container of FIG. I is rotated about its axis at a speed generating suflicient centrifugal force to move the product 13 of FIG. 1 radially outwardly, to become the densely compacted product 17 of FIG. 2. It will be seen that the compacted product 17 is uniformly compacted against the container wall so as to be free of the external voids l and thereby seal the piston 9. Preferably, the speed and direction of spinning are such that the compacted product 17 also is free of the entrapped air pockets 16.

product will be In so compacting the material 17, a central, axial space 18 remains, and this space will contain the air which has been driven out of the product by such compacting. The packaged product can be left in this condition, and when nozzle 6 is first actuated there will be an initial escape of air from the central space 18. Following this, the product will be dispensed in a continuous, unbroken stream of uniform consistency. There will be no disruption of the product stream being dispensed, and by preventing the escape of propellant gas from chamber 12 there will be as complete a dispensing of the product as can be obtained with a container of this type.

Obviously, this method can be carried out using various types of apparatus. One type, in FIG. 4, comprises a platform 20, which can be dished like the container bottom wall 2 and which is supported by bearings 21 for rotation about the axis of the container. Platform 20 is mounted on a resiliently yieldable base 22 containing a spring 23. Nozzle S is engaged by a chuck 24,- driven by the shaft of a motor 25 to rotate the container at high speed about its axis, and spring 23 holds the nozzle engaged with the chuck.

The speed of rotation necessary to accomplish the desired compacting will vary, depending upon the rheological properties of the product being compacted, and upon the' extent of compacting desired. In some cases, it may be desired to eliminate only the external voids 15 to the extent required for proper operation of the piston. In other cases, it may be desired to eliminate the larger internal pockets 16 as well. In other situations, complete deaeration of the product may be desired.

In an effort to determine the efiectiveness of this method in providing a seal for the piston, three identical cans were filled, one with SO'grams of an icing product, one with grams of the same product, and the third with 177 grams of the product. The cans were rotated, about their axes, at high speed, and then gassed with 100 lbs. p.s.i. of nitrogen, following which they were tested by dispensing the product. Even the cans which were less than full, having only 50 and 100 grams, respectively, of the product, expelled the product without lossof propellant gas. There was a short, initial puff of gas, comprising the air forced from voids in the product and collected in the center area 18, but this preceded the flow of the product. After this initial, short puff of air the product flow was uniform and continuous, like the flow of the fully filled can. Therefore, the effectiveness of this method does not require that the product chamber 11 be filled, so long as there is enough product to be compacted against the side wall of the chainber.

In anothei test, a can filled only in the usual manner, and which had blown-by and ceased to function with product remaining in the can, was treated according to the invention. In other words, the non-functioning can was rotated, in this instance, about its longitudinal axis at a speed generating sufficient centrifugal force to compact the product remaining in the can against the chamber wall. The container then was regassed, in the usual manner. When tested, the remaining product was dispensed uniformly and continuously, without disruption or further escape of propellant.

The rotation need not be about the longitudinal axis of the container. Instead, the container could be rotated about an axis extending at right angles to the longitudinal axis, at a point spaced from piston 9 in the direction of dispensing nozzle 6. If, for example, the container were rotated in the plane of the paper, about an axis extending normal to the paper adjacent nozzle 6, the product would be compacted in the manner illustrated in FIG. 3. Here, the compacted product 17' is moved toward the piston and the container wall, to produce the desired sealing of the piston and deaerating of the product. The upper end of the product will be slightly dished, as indicated at 20, and this will comprise the air space.

In carrying out the method of this invention, the container is rotated at sufficient speed about an axis in a direction generating centrifugal force sufficient to move the product outwardly against the container wall for the desired sealing effect. This can be done after the product has been introduced into the chamber 11, or while it is being introduced into the chamber. Gassing of the container can be done after the product has been introduced into the chamber 11, either before or after compacting of the product by the method of the invention.

Accordingly, it is seen that the method of this invention fully accomplishes its intended objects. With this method, a complete range of viscous, slow-flowing products can be successfully packaged and dispensed in a pressurized container. Materials other than those specifically mentioned, including materials as viscous as putty, can be successfully packaged with this method, and this method is useful with containers other than that shown.

Having fully disclosed and completely described this invention, together with its mode of operation, what is claimed as new is:

1. The method of packaging a viscous product in a pressurized dispensing container of the type having a valved dispensing opening which is normally closed, a piston freely movable lengthwise of the container and dividing the container into a product chamber and a propellant chamber, which method comprises introducing the viscous product into the product chamber and the propellant into the propellant chamber, sealing the dispensing opening in the container and rotating the container in a direction and at a speed producing suificient centrifugal force to compact the product against the container wall at the piston sutficiently to seal the piston to prevent the 5 a escape of propellant from the propellant chamber into the leased therefrom in advance of the product upon opening product chamber. the normally closed valve.

2. The method according to claim 1 wherein the centrifugal force also operates to substantially deaerate the References Cited m the file of thls patent product and confine any air occluded in the product and 5 UNITED STATES PATENTS between the product and the Wall of the product Cham- 1,218,416 Krarup Mar. 6, 1917 ber to a location within said product chamber to be rc- 2,895,650 Mahon et a1 July 21, 1959 

1. THE METHOD OF PACKAGING A VISCOUS PRODUCT IN A PRESSURIZED DISPENSING CONTAINER OF THE TYPE HAVING A VALVED DISPENSING OPENING WHICH IS NORMALLY CLOSED, A PISTON FREELY MOVABLE LENGTHWISE OF THE CONTAINER AND DIVIDING THE CONTAINER INTO A PRODUCT CHAMBER AND A PROPELLANT CHAMBER, WHICH METHOD COMPRISES INTRODUCING THE VISCOUS PRODUCT INTO THE PRODUCT CHAMBER AND THE PROPELLANT INTO THE PROPELLANT CHAMBER, SEALING THE DISPENSING 